Measuring instrument



Feb. 13, 1951 H. SCHMOLL MEASURING INSTRUMENT Fi led Feb. 19, 1946 F'Lq- Fig-3 INVENTOR. Hf/VRY 5c HMOLL BY 47r W h A OQA/EY Pat nted Feb- ,1951

UNITED STATES PATENT OFFICE 2,541,891 MEASURING INSTRUMENT fienry Schmoll, Par-ma, Ohio Application February 19, 1946, Serial No. 648,653 6 Claims. (01. 33-169) This invention relates to precision measuring instruments of the class technically known as precision gage blocks. The blocks are usually identified in machine shops as Johansson or J blocks and for purposes of discussion herein they will be identifiecl'simply as gage blocks. Gage blocks are sold in sets and are very expensive. Their use to obtain measurements in the most frequently used fractional dimensions of an inch (i. e. down to divisions) often requires timestaking computation. Moreover, in order to obtain a full range of fractional dimensions such as mentioned several blocks must, in most cases, be carefully selected and wrung together, thus introducing chances of error in their manipulation due, for example, to accumulations of foreign matter on the individual blocks, though sometimes because of lack of skill on part of the user. The individual surfaces of all the blocks used must afterward be carefully wiped off and the blocks must be returned to the proper places in the set. The above discussion indicates the need for a simpler system of preicsion distance measurement in commonly used fractional dimensions; and an object of the present invention is to provide one such simpler system.

Line scribing of work to be machined is generally done either by an adjustable height gage equipped with a scriber or by holding a scriber bar on top of a stack of gage blocks built up to the required height and then moving the assembly to scribing position on a surface plate. Use of the adjustable height gage usually requires the timestaking prelminary operation of assembling the proper number of gage blocks in order to set the scriber point, and when the scribing is done directly from a built up set of gage blocks it is diflicult to hold the scriber in position on the top block. If several gage blocks are required then it is difficult to keep the latter from sliding out of place while scribing. One problem solved by the instrument hereof is to reduce the time required in accurate scribing of lines, thu indicating a further object hereof.

Another object is to provide in connection. with a stepped base block an auxiliary block for obtaining all the necessary divisions of a desired unit of length smaller than the divisions afforded by the scriber bars and base but furnishing stable supports for such scriber bars.

A further object is to provide a stepped precision gage block made as one piece of metal.

Another object is to provide a precision gage block set requiring only a very few individual pieces to obtain measurements and scribe marks in a large number of divisions of an inch or other unit.

A still further object is to provide a gage block set including two or more (e. g.) scriber tools and a multiple surface base block, which tools can be used with the base block to multiply the distance values affordable by the base block alone and enable the circle center and several tangent lines for the circle to be formed quickly and with extreme accuracy.

Other objects and the special advantages of the present invention will become apparent from the following description of the illustrative form or forms. The specific dimensions given in connection with said forms are for example only.

In the drawing:

Fig. 1 is a perspective view showing the main or base block and one form of auxiliary block or bar in the form of a scriber;

Fig. 2 is a similar view showing a different auxiliary block or bar in the form of a stepped scriber;

Fig. 3 is a side elevation showing use of the set for scribing, using thhe scriber according to Fig. 2; A

Fig. 4 is a top view ofthe scriber shown in Fig. 3;

Fig. 5 is an end view of the base block and one scriber in one of several relative positions, enabling boxing in of a circle on a work piece;

Fig. 6 and '7 are end views showing modified auxiliary blocks in typical'positions on the base block.

' at 4 forming the third side or hypotenuse of the triangle. Parallel end surfaces 5 and 6 (Fig. 3) are also preferably formed as fiducial reference surfaces, in which case their spacing is somewhat different from any other dimension that can be measured by the block with or without use of the auxiliary blocks or scriber tools l0 and 3%? of Figs. 1 and 2 respectively. V

The block l is of high grade steel or other hard wear resisting metal which will not become permanently changed in shape or size by temperature variations. It is preferably made and finished the same way as are precision gage blocks, the making whereof is known to the public at the present time. The fiducial surfaces 2, 3, 5 and 5 are preferably planar but, being farly large, may be relieved inwardly from their boundaries 3 to reduce the area of surface contact or for other purposes.

All the measuring surfaces and reference surfaces are carefully lapped to obtain as nearly as possible correct size within a few millionths of an inch. The pieces, before final finish is effected, are seasoned for a time at appropriate subzero temperatures to make certain that the molecular structure of the metal will remain stable.

Referring to the .steps 4, those in the position of the block I shown inFig. 1 start with a height as measured by the distance between the surface I and the base surface 2 of A" as indicated on the drawing. The remaining steps are each exactly A higher than the next preceding one, which is to say the step surface It is above the reference surface 2, the surface I! is the surface It is '7 and the top surface I9 is 1 All the surfaces I5 to [9 inclusive are strictly parallel to the base or reference surface 2 of the block. It will be apparent that the block alone in the position shown by Fig. 1 is capable of affording five different measurements, and that each surface I 5 to I9 inclusive is of adequate size to receive contact with .a dial indicator feeler as of a comparator and that, .assumingappropriate clearance on pieces to be measured,- the block may be used as a Slip gage.

When the block is placed with .its reference surface 3 in contact with (e. g.) afsurface plate, the portions of the steps which'for'm the risers in the position of the block shown by Fig. 2 become the height measuring surfaces. An appropriate arrangement of distances is 'to have the first step 2!) measure A" from the'reference surface andthe other steps 2|, 22, 23 and 24 each successively higher than the next adjacent step. Thus the single block, without any assistance, by selective reversal of base surfaces, affords ten different commonly used fractional measurements at increments. The two sets of surfaces I5I9 and 2024 are preferably separated from each other by relief grooves such as shown at '25 to 'facilitategrinding and lapping.

The bars I Q and 3!! are both made and finished as precision instruments, for example the same as gage blocks are made and finished.

The bar II] in the particular measurementsystem provided by the set has /32" as one transverse dimension and /16 as the other. Those dimensions may .beconsidered the two heights of the bar when used either for scribing or as a gage block. The bar I0 is in the form of astraight scriber, being beveled at its ends to provide scriber edges I'fiand ID" in intersecting -planes,thus affording two sharp points at each corner which can be resharpenedprecisionally simply by regrinding the bevels.

When the bar It! is placed on one of the steps of the block I in the manner indicated in Fig. l, the edge IEJ' scribes a line exactly /16 above the height of the selected step or, as shown, /1s" above the base surface 2. If the bar It is inverted then the scribed line .is at the height (above surface 2.) of thestep on which'the bar is held. similarly the edge IB" can be used to scribe at two different elevations.

The stepped scriber bar 30 preferably has its beveled points lying half way between the associated wide and'narrowsides of the bar, as shown by Figs. 3 and 4, so that a scribed line made by the point 36' (see Fig. 3) is always at the same height in either of two relatively inverted positions of the bar and so that the point 3E! always scribes at the same height (see .Fig. 4) regardmeasures /64" and the flange 43 /64.

formed as precision surfaces strictly parallel to the opposite faces of the bar.

It will be evident that to measure height above an given surface one lays the stepped scriber bar 39 on the surface in the position shown by Fig. 4., wherein the surface is indicated at S.

To measure one uses only the stepped scriber bar 38 turned the proper side up, that is inverted from the positions shown by Figs. 2 and 3, and makes measuring contact with the then upwardly facing step 26. To measure /8 the step I5 of the block I is used and toscribe to that height one uses either end of the straight scriber bar Ill, point down. To measure or scribe one uses the straight scriber bar in the position shown by Fig. 1, reversed ,but on a surface plate or its equivalent. To measure the scriber bar I0 is used in the position shown by Fig. 1, and for scribing 'to that height the edge I0 is upwardly of the bar. To measure or scribe to a height of 5" one places the stepped scriber bar on the first step i 5 of the block I in the position of the latter according to Fig. 1 and with the measuring face 26 of point '39 upwardly. For A" the step 20 and straight scriber is used; and from that height up to the highest step 24 of the block I in the position of the latter shown by Fig.2 all divisions are available in steps. The highest that may be reached with the aid of one scriber bar is 1%, that being with the straight scriber placed with its dimension vertically on the step 24 of the block I. The two scriber bars may of course be stacked for some additional height.

Other height measurements can be had with the block I stood on end, the block shown being 1% long as indicated decimally in Figs. 1 and 2.

In each of the most commonly used scribing positions of the scriber bars the latter are held against respective vertical and horizontal faces of the block I as by the thumb and fingers of the hand, making the set very stable and easily manipulated.

.If it is desired to provide for dividing the measurement increments into 64ths of an inch the auxiliary angle blocks M3 and 45' of Figs. 6 and '7 respectively may be used individually or complementing each other and in combination with the block I and/or the .scriber bars I8 and 30. The flanges 42 and 43 or 42" and 43 of the angle blocks are preferably slighly less than /4 wide measured from the intersection points of the inside faces.

Each of the angle blocks '40 and 4| can be used to obtain respective height measurements in four different positions, one only of each being illus-- trated. Assuming the flange 42 of block 49 Assuming further that the flanges 42 and 43' of the angle block l measure respectively /64" and /64", one can apply the blocks 452 and ll individually to the various stair steps of the main block I either in such manner that th stair steps fit against the inside surfaces of the angle blocks as illustrated or so that the step and riser surfaces of the block I engage respectively the outside flange faces of the angle blocks. Thus,

V 5 when using the stepped block I as a base, one is enabled to start with a minimum height measurement of /64" when the flange :2 of the angle block 48 is resting upon the step i5 of the base block I and with the latter positioned as shown in Fig. 1. The angle blocks 4t and M can, of course, be used directly on a surface plate individually or in nested or stacked arrangement with each other (not necessary) and in stacked relation to either scriber bar is or 3E! in selected rotated positions of the scriber bars described.

Starting with a minimum measurement of /6 when the thinest angle block flange (42) is resting on a surface plate, the /64" increments up to /1e" (repeating for greater heights) are obtained as follows:

/1s": scriber bar 30; /64": flange 43 of angle block 19; /32": scriber bar 39; /64": flange 42" of angle block ll; /8: step E5 of main block I; /64": step 43' of angle block 4!; /32": scriber bar /64": main block step i with flange c2 of angle block 49; /1s: scriber bar Hi; /64: scriber bar ii] /32) with flange 42 of angle block 5!]; /32: step 55 of main block with scriber bar 39 /32"); /64": step 55 of main block I with flange 42' of angle block ti; /4": step 20 of block I; /64": step 55 of block l with flange 43' of angle block M; /32: step [5 of block I with scriber bar I!) /32"); /64": step 26 of block I with flange 42 of angle block 4!); /1s": step 28 of block l with scriber bar 38 In all the different combinations necessary to obtain /64" increments, it is never necessary to use more than three blocks or pieces at a time and, when using the angle blocks on the base block i for scribing, the selected scriber bar can be used to hold the angle block on the base block against displacement perpendicular to the riser faces of the steps. With a scriber bar placed on any selected face of the angle blocks, the

scriber may be held against an aligning vertical or riser face of the base block to steady the scribing operation, except of course whenthe angle blocks are in their topmost positions (resting on the faces I9 or 24 of the base block). The angle blocks 4c and M are preferably the same length as the base block 6 and made without scribers.

The representation of a boxed circle on I a work piece W in Fig. 5 is illustrative of one use of the set. The parallel lines a, b and c were scribed by placing the straight scriber iii successively on the faces 2!, 22 and 23 edge down and sliding the work on the surface plate S past the scriber edges or by sliding the assembled base block and scriber past the work. Then with the work piece rotated 90 so that, for example, reference surface (1 of the work piece is in contact with the surface plate, the other lines e, ,f and g are similarly scribed the proper distance from the reference surface d by means of the base block i and appropriate scriber bar. Thus, the intersection h of lines I) and determines the center of a hole, for example, to be bored in the piece W. Any initial runout of the drill or boring .tool can .be detected by failure of the circle I-I defining the hole to be tangent to the boxing lines a, 0, etc.

A. typical feeler L of a dial indicator is shown in Fig. 5 resting on one of the steps of the base block. Such measuring or instrument checking contact would be made similarly with the uppermost faces or step faces of the scriber bars or with the angle blocks 46 and 4!.

I claim:

1. A precision measuring instrument of the gage block class, comprising an integral metal block having two relatively fixed flducial surfaces at right angles to each other and a plurality of steps forming a hypotenuse portion of the block and presenting a set of measuring surfaces parallel to one of the flducial surfaces and disposed equal distances apart and another set of measuring surfaces parallel to the other flducial surface and disposed equal distances apart, the measuring surfaces of one set which are disposed nearest the associated fiducial surface being closer to the latter than are the corresponding measuring surfaces of the other set with reference to their associated flducial surface, whereby each set of step surfaces affords a series of regularly increasing height measurements above a reference surface on which the fiducial surfaces may be placed selectivelywhich height measurements are all different from those afforded by'the other set.

2. A precision measuring set comprising an integral right triangular metal block with a hypotenuse portion of stair step form and a scriber bar adapted to be supported in two difierent rotated positions of the bar about its axis selectively on either set of step faces and in face to face contact therewith, said scriber car being useable as a gage block to obtain different height measurements on each step when rotated as mentioned and being beveled in directions at right angles to each other at opposite ends to provide a scriber edge and associated paired points, which edges are in intersecting relation hip appropriate to the desired rotated positions of the bar.

3. A. precis on measuring set comprising an integral. right triangular metal block with a hypotenuse portion comprising faces in the form of stair steps, and a scriber bar of rectangular cross section, said bar being supportable selectively in face to face contact with the step faces for use as a block and. having its scriber edge located eouidistantlv from opposite parallel faces of the bar so that the bar may be reversibly positioned to scribe a line at a single reuuired height.

4. The set according to claim 3, wherein the bar stepped bevel formed scriber points in interseating planes parallel to respectively different measuring faces of the bar.

5. A precision measuring instrument of the gage block class, comprising a generally triangular integral metal block having two flducially surfaced sides at right angles to each other and usable selectively as bases capable of stably supporting the block in position a connecting or hypotenuse side comprising two series of steps providing two sets of precisionally formed surfaces all parallel to respective base sides, all the step surfaces of each individual set being of equal increments but the increments of the two sets being different from each other and all the step surfaces of one set being spaced differently from the associated base side than are all the step surfaces of the other set from their associated base side.

A precision measuring set comprising an integral right triangular metal block of ample dimensions for stable self support on four sides, two of said sides comprising flducial base faces at right angles to each other and the block having a hypotenuse portion of stair step form and wit flducial steps in relation to respective relatively opposite flducial base faces and of the same length as said faces measured normal to the other two faces, and an elongated bar with at least two sets of opposite parallel main faces differently spaced apart and complementing the measurements affordable by the stair steps as described,

said bar beingthereby selectlvely usable as a 697 701 gage block on the step faces to provide different 1,433,559 thickness measurements in respectively different 5 1,4911); rotated positions of the bar about its longitudinal 2,345424 axis. 2,372,368

HENRY SCHMOLL. 400 441 REFERENCES CITED 10 The following references are of record in the file of this patent:

UNITED STATES. PATENTS Name Date Ayer Apr. 15, 1902 Lowenstein Oct. 31, 1922 Hoke Apr. 22, 1924 Pfeifer Mar. 28, 1944 Dierking Mar. 2'7, 1945 Scone May 14, 1946 OTHER REFERENCES Publication: Johansson Catalog No. 1'7, June 45 

